hobbes VS ppx_deriving

https://github.com/morganstanley/hobbes

Things like structural equality and ordering are user functions here rather than magic internal definitions (e.g. equality is defined as a type class, and type class instances can deconstruct algebraic types at compile time to decide how to implement instances). But evaluation is eager by default, so it's pretty easy to reason about performance. And data structures can be persisted to files and/or shared transparently in memory with C/C++ programs without translation, also very convenient for the places where this was used. Actually we built some very big and complicated time series databases with it, used in both pre and post trade settings where ~15% of daily US equity trades happen. So I think these observations are useful and have passed through some pretty significant real tests.

Have a look at Hobbes from Morgan Stanley

https://github.com/morganstanley/hobbes

This approach has several benefits, but there's a lot of appeal also to the way they're doing it, to have the same PL across stages (and then maybe have more than just two stages).

> You gave a beautiful answer about programming language

You do the same thing as in Rust, Scala or Haskell and derive the printer [1]. Then at the callsite, if you know the type then you do `T.show` to print it or `T.eq`. If you don't know the type, then you pass it in at the top level as a module and then do `T.show` or `T.eq`.

> Or to convert one type into another type?

If you want to convert a type, then you have a type that you want to convert from such as foo and bar, then you do `Foo.to_bar value`.

We can keep going, but you can get the point.

You _can't_ judge a language by doing what you want to do with one language in another. If I judge Rust by writing recursive data structures and complaining about performance and verbosity that's not particularly fair correct? I can't say that Dart is terrible for desktop because I can't use chrome developer tools on its canvas output and ignore it's hot-reloading server. I can't say Common Lisp code is unreadable because I don't have type annotations and ignore the REPL for introspection.

[1] https://github.com/ocaml-ppx/ppx_deriving

Ocaml has the amazing ppx_deriving which can be used for serialization / deserialization in various formats.

I wrote a CLI tool and I'd like to produce statically linked binaries of my tool. However, I cannot do this because I'm using the ppx_deriving deriving preprocessor, and I cannot produce a statically linked executable while using this package.

Not great, not terrible; the language supports annotations which mean nothing to the compiler but which pre-processors can take advantage of, and there is a framework called ppx which you can use to write your own preprocessor. There exist many pre-processors to do things like add inline tests, generate getter/setter/pretty-printing functions, and so on. Here is an example:

https://github.com/ocaml-ppx/ppx_deriving

is from https://github.com/ocaml-ppx/ppx_deriving

Have you tried to derive a print function using https://github.com/ocaml-ppx/ppx_deriving

However, there is a ppx (a pre-processor) which can do the job : ppx_deriving. You just have to anotate your type in oder to get the compare function automatically generated :